Manual liquid metering device and cartridge

ABSTRACT

Housing is generally tubular and split into two longitudinal hinged halves. Housing receives threads on driver. Retention and anti-rotation means retain cartridge in other end of housing. Cartridge has zero draft tubular wall, and rounds to an extended tip with external threads at other end. Tip is hollow. Piston matching profile to tip and seals open end of cartridge. Liquid is contained between tip and piston. In use, driver engages piston to force liquid out tip. Cartridge differentiates between capacities of cartridge for housing. Driver and housing indicate rotary position of driver with respect to housing and prevent driver from reversing direction. Injector is designed to withstand pressures of operating system to which liquid is injected. Injector high accuracy for use with high concentrations and small cartridges. Cartridge and piston limits introduction of air when filling and limits retained liquid after cartridge used. Housing and driver indicate liquid remaining.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of InternationalApplication PCT/CA2004/000114 filed 29 Jan. 2004 which claims thebenefit of the filing date of U.S. Provisional Patent Application Ser.No. 60/443,532 filed 30 Jan. 2003 under the same title.

TECHNICAL FIELD

The invention relates to devices for manually metering liquid, and tocartridges for use with such devices. It also relates to such devicesfor injecting liquids into pressurized systems, such as air conditioningand refrigeration systems.

BACKGROUND ART

Manually metering of liquids can be difficult. This can be seen when onewants to get a certain amount of liquid (but not all of it) out of atube. The tube collapses and there is no precise way of determining howmuch has been used or how much is left, short of using a measuringdevice such as a weigh scale. This is often not practical, particularlywhere work is being performed on a chargeable basis. Syringes and otherinjectors have been used for many applications, such as metering ofepoxy resins and hardener. They typically lack precision.

Where one is injecting liquids into a pressurized system it may even bedifficult simply to inject the entirety of the liquid.

As an example of circumstances where it is desired to meter liquids,injectors are often used in air conditioning and refrigeration systems.Such systems often leak which is undesirable. In air conditioning orrefrigeration applications the system will not operate efficiently withreduced quantities of refrigerant. The missing refrigerant needs to bereplaced. It is also undesirable as refrigerant can be environmentallydamaging when released.

Leak detection can be performed by injecting a fluorescent dye into thesystem. In air conditioning and refrigeration applications dyestypically used for this purpose fluoresce in the ultraviolet and nearultraviolet region from approximately 360 to 420 nm; so, an ultravioletlight is shone on the system. Wherever leaks occur the dye will escapethe system and fluoresce under the light. A pulsing ultraviolet lightfor this purpose is described in U.S. Pat. No. 5,804,822 issued Sep. 8,1998 under title Fault Locating Device, System and Method. Many otherultraviolet lights are available.

A number of injectors have been developed for getting liquids into airconditioning and refrigeration systems. Some injectors may also be usedto inject other liquids, for example, refrigerant, lubricant and/orother additives into the air conditioning system.

The assignee of the instant application is the owner of U.S. Pat. No.6,263,778 issued Jul. 24, 2001 under title Precision Liquid InjectionSystem. The system has a spindle with a central bore into which a pistonis inserted. The piston and spindle define a chamber that carries theliquid to be injected. A driver sleeve has interior threads that matchthose on the outside of the spindle. A piston rod is placed inside thedriver sleeve. Rotation of the driver sleeve causes the piston rod todrive the piston into the chamber. The liquid escapes through an openingat the end of the spindle and is injected in to the system.

Although the system works well, improvements are desirable as with anyproduct.

It is an object of the invention to provide such improvements, toaddress other problems associated liquid injectors, or to providealternative devices.

DISCLOSURE OF THE INVENTION

In a first aspect the invention provides an injector for injecting aliquid into a pressurized system. The injector has a cartridge forcontaining the liquid, the cartridge having along its longitudinal axisan open end and an opposing partially enclosed end with a connector forconnection, directly or indirectly, to the pressurized system, agenerally tubular housing for receiving the open end of the cartridge,the housing having internal threads, a driver having external threadscompatible with the internal threads of the housing and having a handle.An operator can manually grip the housing while rotating the driver withrespect to the housing to force the liquid to be ejected from thecartridge through the enclosed end.

The connector may be a tip extending from the cartridge, the tip havingexternal threads. The handle and the housing where it is to be grippedmay be fully accessible to an operator throughout the travel of thedriver into the housing. The housing may have a grip formed from a slipresistant material. The material may be a rubber-like material,including rubber.

The housing may have two longitudinal halves. The housing halves may belongitudinally hinged. The cartridge and housing may have anti-rotationmeans to prevent rotation of the cartridge with respect to the housingabout the longitudinal axis of the housing. The cartridge and housingmay have retention means to prevent movement of the cartridge along thelongitudinal axis of the housing when the injector is connected to thepressurized system.

The housing may have a lock with a first and second position, the lockpermitting opening of the housing halves when in the first position andthe lock preventing opening of the housing halves when in the secondposition. The lock and a first of the housing halves may have a slideand track mechanism to permit limited motion of the lock between thefirst and second positions. The second housing half may have a tabwhich, when the housing is being hinged open or closed, can pass thelock when the lock is in the first position and cannot pass the lockwhen the lock is in the second position. The lock may have a lock springthat tends to keep the lock closed when it is closed and tends to keepthe lock open when it is open.

The housing and driver may have rotary position indicator means thatprovide an indication of the rotary position of the driver with respectto the housing. The rotary position indicator means may provide anaudible click when aligning to a selected rotary position.

The housing and driver may have anti-reverse means that prevent therotary movement of the driver with respect to the housing about thelongitudinal axis of the housing in one direction, while permitting suchmotion in the other rotary direction.

The driver may have a longitudinal groove in the threads and the housingmay have a lock spring with a latch that springs into the groove whenthe groove and latch are aligned and that is pushed away by the threadswhen the groove and latch are not aligned. The groove may have asubstantially perpendicular leading edge, and the latch may have asharply inclined trailing edge. The lock spring may be sufficientlystiff to provide an audible click when the latch enters the groove.

The cartridge and housing may have differentiation means to permit thehousing to differentiate between cartridges of different capacities. Thehousing may have a plurality of locations for cartridges of differentcapacities. The housing locations may be different to permit the housingto differentiate between cartridges of different capacities.

The cartridge may have an annular flange extending outwardly about theopen end, and the housing halves may have respective slots for receivingthe flange and limiting movement of the cartridge along the longitudinalaxis of the housing. The flange may be asymmetrical about thelongitudinal axis of the housing and the slots may be correspondinglyasymmetrical to prevent rotary movement of the cartridge about thelongitudinal axis of the housing. The flange may have two flat sectionsopposing one another across the longitudinal axis of the cartridge, andthe slots have corresponding flat sections, whereby rotation of thecartridge with respect to the housing is prevented when the cartridge ismounted in the slots.

A first cartridge capacity may have a flange of a first thickness, andwith the slots in the housing for that cartridge capacity are of acorresponding size. A second cartridge capacity may have a flange ofsecond thickness greater than the first thickness, and with the slots inthe housing for that cartridge capacity of a corresponding secondthickness, wherein cartridge of the second capacity cannot be placed inthe slots for the first cartridge capacity. A smaller cartridge capacityhousing slot may be located further from the housing threads than alarger cartridge capacity housing slot. The housing and driver may havelongitudinal indicator means that indicate the amount of liquidremaining in the cartridge. The driver may have indicators or numericalindications longitudinally spaced along its surface. The housing mayhave means to isolate a given indicator on the driver for thelongitudinal position of the driver. The housing may have means toisolate a given indicator on the driver for the rotational position ofthe driver. The housing may have an indicator window that isolates agiven numerical indication on the driver for the longitudinal positionof the driver. The numerical indication may be an indication of theamount of liquid left in the cartridge. The numerical indication may bethe number of doses left in the cartridge.

The cartridge may be made from a polyolefin. The cartridge may be madefrom polypropylene generally 0.094 inches thick, the cartridge has atubular wall section of zero draft and approximate 0.812 inches internaldiameter rounding into a converging shoulder with a radius of 0.406inches. The cartridge may have an annular flange of approximately 1.240inches external diameter extending about the open end of the cartridge.The flange may have two flats opposing one another across thelongitudinal axis of the cartridge and separated by a distance ofapproximately 1.08 inches. The cartridge may have a 25 dose capacity ofliquid fluorescent dye for an automobile air conditioning system. Theinternal axial tip length of the cartridge may be approximately 0.640inches and the overall length of the cartridge may be approximately 5.31inches.

The cartridge may have an annular flange of approximately 1.250 inchesexternal diameter extending about the open end of the cartridge. Theflange may have two flats opposing one another across the longitudinalaxis of the cartridge and separated by a distance of approximately 1.032inches. The cartridge may have a single dose capacity of fluorescent dyefor an automobile air conditioning system. The internal axial tip lengthof the cartridge may be approximately 0.640 inches and the overalllength of the cartridge may be approximately 2.25 inches.

The driver may be hollow. The cartridge may have a piston having anexternal profile matching the internal profile of the cartridge in thetip, the piston enclosing the open end of the cartridge to provide achamber within the cartridge for the liquid. The tip of the cartridgeand the tip of the injector may externally align when the piston isfully inserted into the cartridge. The cartridge may be releasablysealed at the tip when the cartridge is filled with liquid. Thecartridge may be sealed at the tip with a cap when the cartridge isfilled with liquid.

The liquid may contain a fluorescent dye compatible with refrigerant inthe pressurized system, for example R12, R22, R134A, R410A, R406, R404,R502 or ammonia refrigerant. The injector may be able to withstandinternal pressure of 150 psi. The injector may have no significantdeflection at 150 psi. The cartridge may contain a high concentrationliquid, for example the liquid may be a liquid fluorescent dye having aconcentration such that 1.2 ml of the dye is sufficient to perform leakdetection for every 7 lbs of refrigerant in the system or for every 4lbs of refrigerant on the system.

In another aspect the invention provides a liquid metering device formetering a liquid. The device has a cartridge for containing the liquid,the cartridge having along its longitudinal axis an open end and anopposing partially enclosed end with a tip extending from the cartridgethrough which the liquid is dispensed from the cartridge, a generallytubular housing for receiving the open end of the cartridge (the housinghaving internal threads), and a driver having external threadscompatible with the internal threads of the housing, and the driverhaving a handle. An operator can manually grip the housing whilerotating the driver with respect to the housing to force the liquid tobe ejected from the cartridge through the partially enclosed end.

In other aspects the invention provides metering devices, injectors,cartridges, housings and drivers as set out above and methods of usetherefor, and metering devices, injectors, cartridges, housings anddrivers and methods of use therefore as further described elsewhere inthis description, or as may be based thereon or incorporate variousfeatures or uses thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention and to show morewere clearly how it may be carried into effect, reference will now bemade, by way of example, to the accompanying drawings which show thepreferred embodiment of the present invention and in which:

FIG. 1 is a side view from the left of an injector, including cartridge,housing and driver, in accordance with a preferred embodiment of theinvention,

FIG. 2 is an exploded perspective view of the injector of FIG. 1 fromabove and to the right of the injector,

FIG. 3 is an axial cross-section of the cartridge of FIG. 1,

FIG. 4 is an end view of the cartridge of FIG. 1 looking in its openend,

FIG. 5 is an axial cross-section of a piston for use with the cartridgeof FIG. 1,

FIG. 6 is a side view of a cartridge in accordance with an alternatepreferred embodiment of the invention,

FIG. 7 is a front view of a right half of the housing of FIG. 1,

FIG. 8 is an end view of the housing half of FIG. 7 from below,

FIG. 9 is a cross-section of the housing half of FIG. 7 through acartridge slot and looking up,

FIG. 10 is a front view of a left half housing of FIG. 1,

FIG. 11 is a cross-section of the housing half of FIG. 10 through acartridge slot and looking up,

FIG. 12 is a cross-section of the housing half of FIG. 10 through a lockspring mount and looking up,

FIG. 13 is an end view of the housing half of FIG. 10 from below,

FIG. 14 is a side view of the driver of FIG. 1,

FIG. 15 is an end view of the driver of FIG. 1,

FIG. 16 is a side view of a driver in accordance with an alternatepreferred embodiment of the invention for use,

FIG. 17 is a side view of an injector in accordance with an alternatepreferred embodiment of the invention, using the housing of FIG. 1, thecartridge of FIG. 6 and the driver of FIG. 16,

FIG. 18 is a rear view of a lock used with the housing of FIG. 1,

FIG. 19 is a longitudinal cross-section of the lock looking to theright,

FIG. 20 is a rear perspective view of a rubber-like grip from FIG. 1,

FIG. 21 is a cross-section of the driver of FIG. 1,

FIG. 22 is a partially exploded perspective view of an injector,cartridge and housing in accordance with an alternate embodiment of thepresent invention, and

FIG. 23 is a partially exploded view of an injector, cartridge andhousing in accordance with a further alternate embodiment of the presentinvention.

MODES FOR CARRYING OUT THE INVENTION

In this description similar reference numerals will be used to refer tolike parts in different figures, unless otherwise set out in thisdescription. Terms that imply a specific orientation of the parts withrespect to the external world do not imply that such an orientation isrequired, for example the terms “left” and “right”, and “bottom” and“top”, when used to refer to parts of the preferred embodiment are usedfor convenience only.

Referring to FIG. 1, liquid metering device 1 will typically be used toinject materials into a pressurized system, not shown. It is to berecognized that the device 1 is particularly beneficial for suchapplications; however, it is not limited thereto. Towards the end ofthis description reference is made, for example, to alterations that maybe desirable (although not necessary) when the device 1 is used innon-injection applications. As the primary use of the preferredembodiment is for injection applications, the device 1 will now bereferred to as injector 1. The injector 1 has a driver 3, a housing 5and a cartridge 7. Referring to FIG. 2, the housing 5 is generallytubular and is split into two longitudinal halves 9, 11. The housinghalves 9, 11 may be formed from a sufficiently stiff material thatresists deflection as set out herein, for example glass filled nylon,dye cast aluminum, aluminum or zinc alloys, or sintered metal.

Attached by a screw 12 or otherwise to left half 9 is a first lockspring 13. The lock springs referred to herein are made from springsteel. Many other suitable materials could be used, includingsufficiently elastic and resilient plastic. In FIG. 2, hole 15 isaligned with hole 17, so that the screw 12 can be inserted. Thiscorrectly orients latch 19 of spring 13 to project away from the lefthousing half 9.

Referring to FIGS. 1 through 4, cartridge 7 is generally tubular. At oneend 8 the cartridge 7 is open to receive a piston 23. At the opposingend, the cartridge 7 is partially enclosed to allow the retention ofliquid, while permitting it to be ejected from the cartridge. Thecartridge 7 has a rounded shoulder 27 that decreases the dimension ofthe cartridge 7, and a tip 29, that extends from the shoulder 27. Thetip 29 is hollow and has external threads 30. The liquid is dispensedfrom the cartridge 7 through the tip 29. In the preferred embodiment thethreads 30 are ⅝ inches at 18 threads per inch. The threads 30 allow forconnection of connectors, such as R134A, R22, R12 or other refrigerantsystem (for example, R410A, R406, R404, R502 or ammonia) fittings orhoses with such fittings, not shown, that further connect to an airconditioning, refrigeration or other pressurized system, not shown. Suchconnectors could be integrated with the cartridge 1; however, this mayadd to the cost and restrict the use of the cartridge to systems thatuse that particular fitting. Alternatively, separate fittings could besold with the injector 1, or cartridge 7. No matter which method is usedcare must be taken to ensure that the liquid in the cartridge iscompatible with the other contents of the system into which it is to beinjected, for example R12, R134A, R22, R410A, R405, R404, R502 orammonia air conditioning and refrigeration systems.

The hoses or fittings could have a one-way valve, such as a check valve,that allows liquid flow from the cartridge 7 to the pressurized system,while limiting flow in the reverse direction.

The tip 29 and external threads 30 form a connector for connection,directly or indirectly, to the pressurized system. The tip has abevelled rim 31 to provide a good seal an o-ring type seal that may beused when connecting fittings or other connectors to the tip 29.Alternative connectors could be used in place of the tip 29. Forexample, the tip 29 could be inverted to extend into the cartridge withinternal threads for connection to the pressurized system. A tip 29 withexternal threads is preferable as this provides a smooth internalprofile against which the piston 23 can rest.

Referring to FIGS. 2 and 5, the piston 23 has an external profile thatgenerally matches the internal profile of the cartridge 7 from above theshoulder 27 through the tip 29. Thus the piston 23 also has a roundedshoulder 32 and a tip 33. When the piston is fully inserted into thecartridge, the tip 33 extends to be flush with distal end 35 of tip 29(such that the tips 29, 33 are externally aligned). This fully fills thedistal end of the cartridge 7. The piston 23 is preferably formed(except for an annular seal to be described) from a hard material suchas the same material as the cartridge 7; however, it may be formed fromother sufficiently hard materials that are compatible with the liquid tobe injected. A hard material limits the amount of deflection in thepiston 23 for increased accuracy. Using the same material for the piston23 as the remainder of the cartridge 7 also facilitates recycling of thecartridge 7.

A groove 37 is provided on the piston 23 above the shoulder 32. Anannular seal, such as an O-ring seal, not shown, fits within the groove37 to seal between the piston 23 and the cartridge 7. The seal isdeformable and resilient to fill in the gap between the piston 23 andthe cartridge 7. In the preferred embodiment the piston 23 has anexternal diameter of 0.800 inches, while the internal diameter of thecartridge at the open end 8 is 0.812 inches. Preferably the seal isfairly hard (between 70 and 90 durometer) to reduce the amount offriction between the piston 23 and the cartridge 7. This makes it easierto start the piston 23 in motion when the injector 1 is being used. Thepiston 23 should have sufficient length on either side of the sealsufficiently close to the cartridge 7 about the seal to prevent rotation(flipping) of the piston 23 within the cartridge 7 that might cause thepiston to 23 to jam in the cartridge 7 or to break the seal between thepiston 23 and the cartridge 7.

When the piston 23 is inserted into the cartridge 7 it encloses the openend 8 and forms a chamber within the cartridge 7 to contain the liquid.

Referring again to FIGS. 1 through 4, the cartridge 7 is preferablyfilled through the tip 29 with the piston 23 fully inserted into thecartridge 7. The liquid is introduced under pressure, which causes thepiston 23 to move away from the tip 29. When a desired amount of liquidis introduced, the cartridge 7 is releasably sealed at the tip 29, forexample with a cap threaded onto the threads 30 or a removable thinplastic or foil glued seal, not shown. Once the tip 27 is sealed thepiston 23 will not move as it is also sealed to the cartridge 7 and anysuch motion would create a vacuum or increase the pressure to retain thepiston 23 in position. As the tip 29 and tip 33 begin the fill processflush with one another, the introduction of air into the cartridge 7 isminimized. This can be important for some systems, for example airshould not be introduced into conditioning and refrigeration systems.

Also, after the cartridge 7 is fully used virtually all of the liquid isejected because the profiles of the piston 23 and the cartridge 7 arematched and the tips 29, 33 are flush. This results in less waste andmakes the cartridge 7 easier to recycle.

The cartridge 7 has an annular flange 39 that extends outwardly aboutthe proximal end 41 of the cartridge 7. The flange 39 has two flats 43.The flats 43 are generally parallel and oppose one another across thelongitudinal axis of the cartridge. The flange 39 is used to retain thecartridge 7 in the housing 5 to limit movement along the longitudinalaxis of the housing. As the flange 39 is asymmetrical about thelongitudinal axis of the cartridge, the flats 43 are used to preventrotation of the cartridge 7 in the housing 5. Rotation could loosenconnections or twist hoses between the injector 1 and the airconditioning system. It could also tend to wear the housing over timeand reduce the accuracy of the injector 1. Other retention means andanti-rotation means could be used, such as a full annular flange, notshown, with one or more stop blocks, not shown, extending from theflange toward the tip 29. A corresponding change would have to be madeto the housing 5. Combined retention means and anti-rotation means suchas the flange 39 with flats 43 are useful; however, these functionscould be separated as would be evident to one skilled in the art.

The injector 1 and the cartridge 7 have many features to increase theaccuracy with which a given dose of liquid can be ejected from thecartridge 7. The internal diameter of the cartridge 7 between theshoulder 27 and open end 8 (the “wall” 45) is substantially the same.This is sometimes referred to as “zero draft”. The cartridge 7 is asingle integrally formed unit most easily manufactured usinginjection-moulding techniques. A zero draft cartridge is more difficultto manufacture as the plug that forms the inside of the cartridge 7 ismore difficult to remove; however, this configuration means that equallinear movements of the piston 23 in the cartridge will result in anequal volume of liquid being ejected from the cartridge 7. Also the backpressure is constant and thus also the applied force. This extra hightolerance allows for better prevention of leakage.

In many applications, for example dye injection applications, the liquidis typically injected into an air conditioning system that is underpressure. The pressure can be as high as 150 psi. The preferredembodiment of the cartridge 7 is designed not to deflect while underpressure of 500 psi or more. The injector 7 is preferably made frompolypropylene with a wall thickness of 0.094 inches, overall length (tip29 to open end 8) of 5.31 inches, internal axial tip 29 length of 0.640inches, beginning tip 29 opening of 0.4 inches, ending tip 29 opening of0.3 inches, internal diameter of the wall 45 of 0.812 inches, shoulder27 radius of 0.406 inches, flange 39 external radius of 1.240 inches,flange 39 thickness of 0.094 inches, distance between flats 43 of 1.08inches. Alternative cartridge 7 materials dimension and shapes will beevident to those skilled in the art; these specific dimensions are thosethat have been found to work well for the intended purposes describedabove. The cartridge 7 is preferably clear or translucent to allow anoperator with visual indication of the amount of liquid in the cartridge7.

Where the liquid is a liquid fluorescent dye, it may have a highconcentration such that 1.2 mL or less of the dye is sufficient for each7 lbs. of refrigerant in an air conditioning or refrigeration system.The cartridge 7 with the dimensions described elsewhere herein provides1.2 mL per single rotation of the driver 3. The cartridge 7 has acapacity of approximately 30 mL. The cartridge 7 with the abovedimensions provides a capacity of 25 shots or doses for a typicalautomotive air conditioning system when using high concentration dye.Typically automotive systems have approximately 4-7 lbs of refrigerant.

Of course, other capacities of cartridge can be used. Also, thecartridge 7 could be filled more or less so that the piston 23 starts ata different axial depth. The driver could be rotated more than once forhigher capacity air conditioning or refrigeration systems, or otherapplications such as injection of lubricant, stop leak or otheradditives. High accuracy allows for the use of a high concentration dye.The use of a high concentration dye means a smaller cartridge 7, lesswaste and less foreign material added to the air conditioning system. Asmaller cartridge 7 can also mean higher accuracy as there is less of atendency for the cartridge 7 to stretch or bulge for the same thicknessof material. The injectors described herein are repeatably accurate towithin 0.1 ml or less.

The rounded shoulder 27 also adds to the strength of the cartridge 7 asthe shoulder 27 does not provide a specific point of failure at lowerpressure than the remainder of the cartridge 7.

Referring to FIG. 6, a cartridge 49 is similar to cartridge 7, exceptthat the wall 45 is shortened to provide an overall length of 2.25inches, flange 39 thickness is 0.070 inches, external flange 39 diameteris 1.250 inches, and distance between flats 43 is 1.032 inches. Thereduced length provides a single dye dose capacity. The difference inthe thickness of the flanges 39 of the cartridges 7, 49 is utilized todifferentiate between the cartridges 7, 49 for the housing 5 as isdescribed elsewhere herein. The difference between the flange diametersand distances between flats 43 of cartridges 7, 49 are not exploited inthe preferred embodiment; however, such differences could be used touniquely differentiate the cartridges 7, 49 for the housing 5 as isdescribed elsewhere herein.

Referring to FIGS. 2 and 7 through 13, housing halves 9 and 11 havealternating longitudinal pin holders 51, 53 and 55 that fit together toreceive a single pin 56 and create a clamshell-type longitudinal hinge57. On a bottom portion of the interior of the halves 9, 11 are threads59, 61 that are aligned to create a continuous internal thread forreceiving the driver 3 when the hinge 57 is closed.

The hinged halves 9, 11 permit easy access to the driver 3 and thecartridge 7 for insertion and removal, and for repositioning of thedriver 3. The halves do not have to be hinged in order to do this. Thehalves 9, 11 could be entirely separable and fit together with locks oneither side (similar to the lock 91 that will be described) or othermeans to releasably attach the housing halves. It is also possible tocreate housings that do not need to be opened as will be describedlater.

Each housing half 9, 11 has an annular slot 63, 65 for accepting theflange 39 of cartridge 7 and has an annular slot 67, 69 for receivingthe flange 39 of cartridge 49. The slots are dimensioned to snuglyretain their respective flanges 39 and to fit against the flats 43 asbest seen in FIGS. 9, 11. The difference in the thicknesses of theflanges 39 of cartridges 7 and 49 is reflected in the sizes of the slots63 through 69. Thus, the cartridge 7 will not fit in the slots 67, 69.This is advantageous as the housing 5 can have a large depth (and thus alarge gripping surface) while permitting the tip of cartridge 49 toextend beyond the housing 5 for easy access to the tip 29 forconnection, while having the cartridge 7 closer to the threads 59, 61and reducing the required length of the driver 3.

Although not shown, the cartridges 7, 49 could be uniquelydifferentiated to the housing 5 by using two different parameters, suchas the distance between the flats 43 and the external diameters of theflanges 39, and corresponding sizes of slots 63 through 69. If thedistance between the flats 43 of the cartridge 7 were too large then thecartridge would not fit into the slots 67, 69, and if the diameter ofthe flange 39 of the cartridge 49 was too large then the cartridge 49would not fit into the slots 63, 65. Thus the cartridges 7 and 49 wouldbe uniquely differentiated for the housing 5. Alternate cartridgecapacities and additional housing slots with corresponding uniquedifferentiators could be included as desired.

The two slot positions ensure that the tip 29 of the cartridge 49 isaccessible from outside the housing 5, while providing greater lateralsupport to the longer cartridge 7. Also, the cartridges 7, 49 arecorrectly matched with different drivers as will later be described. Acloser slot position for the cartridge 7 allows for a shorter driver 3and shorter overall injector 1 length. It is possible to use a singleslot position for multiple cartridge capacities and to make the flanges39 and flats 43 the same size for each cartridge capacity. It isdesirable to retain a length of housing 5 that is easy to grip whileturning the driver 3 at all axial locations of the driver 3 (throughoutthe travel of the driver) when the injector 1 is connected to an airconditioning system under pressure.

Referring to FIGS. 2, 10 and 12 the housing half 9 has a lock springmount 71 indented into the housing half 9 between the threads 59 and theslot 63. The mount has a flat section 73 behind which is hole 15. At theopposite end of the mount 71 is a hollow 75 of greater depth than thegeneral indent of the mount 71. The mount 71 receives the lock spring 13previously described with reference to FIG. 2. The hollow 75 allows thespring lock 13 to bend away from the housing 5 axis when the latch 19 ispressed, while springing back to its original position when released.

The housing 5 also has locating bosses 76 a and cups 76 b on therespective halves 9, 11. This assists in locating (aligning) the twohalves 9, 11 with respect to one another when closed. This reduces wearand tear on the hinge 57 and also facilitates proper align of the lock91 with respect to the tabs 115, 117.

Referring to FIG. 14, driver 3 has a handle 77 and a spindle 79 withexternal threads 81. Threads 81 match threads 59, 61 of housing 5. Thehandle 77 is of sufficient length and diameter to be easily gripped. Anoperator is easily able to maintain purchase on the handle 77 and thehousing 5 no matter what the axial position of the driver 3 (throughoutthe travel of the driver).

The use of a threaded spindle 79 provides a great deal of accuracy. Thenumber of threads per inch will depend on the number of turns desiredfor a particular dose and the configuration of the cartridge, amongother things. In the preferred embodiment a single dose is ejected perfull revolution of the driver with 6.8 threads per inch (or apitch=0.147″). For high accuracy, the various threads, housing halvesand other components should also be designed not to deflect at thehighest pressure to be encountered. As mentioned previously, theinjector 1 was designed to withstand 500 psi. The injector 1 could bedesigned not to deflect at lesser pressures, preferably above 150 psi.The housing halves 9, 11 and the driver 3 are formed from a hardplastic, although many other materials can be used, includingpolyolefins (such as polypropylene), metals and composites.

Referring to FIGS. 1 and 15, spindle 79 has longitudinal groove 83running the length of the threads 81. The groove 83 is shaped to receivethe latch 19 of spring lock 13 to provide a positive indication of therotary position of the driver 3. When the driver 3 is rotated the springlock 13 is pressed by the threads 81 away from the axis of the housing 5into the hollow 75. When the groove 83 again meets the latch 19, thespring lock 13 springs the latch 19 back into the groove 83. An audibleclick can be heard. As the latch 19 has a sharply inclined trailing edge85 and the groove has a substantially perpendicular leading edge, thedriver 3 is prevented from reversing direction and backing out of thehousing 5. The housing 5 must be opened in order to reposition thedriver 3 further away from the cartridge 7.

Referring to FIGS. 1, 2, 10 and 13, the housing half 9 has an indicatorwindow 87. Along the groove 83 indicator numbers, not show, can bemoulded. As the driver 3 is rotated to align the groove 83 and latch 19,an indicator number will appear in the window 87. The window isolatesthe indicator number. The numbers are selected to provide an indicationto an operator of how many doses of liquid have been used or how manyare remaining. Typically it will be preferred to indicate the number ofdoses remaining. Alternatively, the indicator numbers can simplyindicate the volume remaining in the cartridge 7, for example 25 ml. Theindicator window 87 could be shifted longitudinally along the housing toprovide a complete 4-sided window, although this may be more difficultto manufacture. It is not actually necessary to have a specific window87 as part of an indication means on the housing 5 and driver 3. Thedriver 3 position indicators could simply be aligned with an edge of thehousing 5. A window 87 is preferable as it also provides a positiveindication of the rotational position of the driver 3 when theindicators are aligned with the window 87.

The parameters of the driver 3, cartridge 7, and housing 5, such as thecartridge depth and circumference, the threads per inch of the housingand driver, and the location of the cartridge within the housing 5 needto be determined in order to determine the start of the indicatornumbers, there spacing and the numbers themselves. Other factors couldbe the required numbers of rotations per dose. If a dose is 3revolutions then the indicator numbers may be spaced accordingly. Theinjectors described herein have many applications and many differentdosage levels may be applicable. It will be advantageous to match thenumerical indicators to the particular application for a selectedinjector.

Referring to FIG. 16, a driver 89 is similar to driver 3; however,driver 89 is shorter and has an extended spindle portion 91 withoutthreads 81. The driver 89 may be used with the housing 5 and thecartridge 49. The driver 89 reduces the overall length of the injectorconsiderably. The extended spindle portion 91 compensates for the changein slot position of the cartridge 49. The threads 81 of driver 89 couldextend to the end of the driver 89; however, this would require theoperator to turn the driver 89 unnecessarily to come into contact withthe piston 23. As the driver 89 is used with a single shot cartridge itis not necessary to provide indicator numbers in groove 83, althoughthis may be done. Although it is not necessary, it is still desirable tohave a groove 83 to retain the latch 19 for positive indication ofdistance travelled and prevent to prevent back rotation of the driver 3.

Referring to FIG. 17, it is evident that device or injector 90, usingcartridge 49 in combination with driver 89, results in a much shorterlength.

Referring to FIGS. 1, 2, 18 and 19, lock 91 has a slide 93 along oneedge that fits within a corresponding track 95 in the left housing half9. There is a cut-out 97 at one end of the slide 93 to allow the lock 91to pass the housing half 9. A second spring lock 99 is mounted to a lockmount 101 inside the lock 91 on pins 103, 105 through holes 107, 109.The pins 103, 105 are melted to weld the spring lock 99 to the mount101. Other retention means, such as screws, could be used.

The halves 9, 11 have two pairs of tabs 111, 113 and 115, 117 that abutone another when the housing 5 is closed. The lock 91 has cut-outs 119,121 to allow the tabs 115, 117 of the right half to pass under the lock91 when the lock is in a first lower position. When the lock 91 is movedupwardly to meet the housing 5, the cut-outs 119, 121 also move upwardlyand the tabs 115, 117 are retained by the lock so that the halves 9, 11cannot be separated.

After the lock 91 is closed, the lock 91 is urged toward the closedposition by spring lock 99 moving against bump 123 on right half 11. Anoperator can open the lock 91 by overcoming the resistance provided bythe spring lock 99 and bump 123 combination to cause the spring lock 99to pass over the bump. The bump 123 then tends to keep the lock 91 open.

The spring lock 99 also prevents the lock 91 from sliding completely outof the housing because the free end of the spring lock 99 will abut thetab 113 and not be allowed to pass over it.

Referring to FIGS. 1, 2 and 20, the right half 11 is finished by arubber-like (such as rubber) grip 125 that provides a comfortable slipresistant surface for the operator to grip. The material used in thepreferred embodiment is Santoprene™. The grip could be formed of othermaterial, such as solid plastic. The grip 125 fills in the externalcontour of the half 11 and may be glued or otherwise affixed thereto.The left half 9 has a similar grip, not shown, that fills in the contourof the left half 9. Other finishes are possible. For example, thehousing halves 9, 11 could each be moulded to provide a grip surface ina unitary construction. The grip surface could have a non-flat contourfor additional grip, for example ridges that generally match those of ahand. The grip 125 is fully accessible for the operator to obtainpurchase no matter what the axial location of the driver 3.

Referring to FIG. 21, the driver 3 may be hollow to reduce the amount ofmaterial used and increase the speed of manufacturing by reducing curingtime. Other drivers, such as driver 89, may be similarly hollowed.

In operation, the housing 5 is unlocked by sliding the lock 91downwardly. The housing 5 is opened by unhinging the housing halves 9,11. A cartridge 7 is placed in slot 63 or 65, or a cartridge 49 isplaced in slot 67 or 69. Driver 3 may be placed in the same half 9 or 11as the cartridge 7 or 9, or, alternatively, if cartridge 49 is used,driver 49 may be used. The housing is then closed by re-hinging thehalves 9, 11 and sliding the lock 91 upwardly. If a driver has notalready been placed in the housing 5, one may be threaded in until theindicator numbers and/or spring lock 13 indicate that the driver is inthe correct position. The cartridge 7 or 49 is unsealed and anappropriate connector is threaded onto the tip 29. The connector is thenconnected, directly or indirectly, to an air conditioning system. Theoperator checks to see the starting position in the indicator window 87.The handle 77 is gripped and rotated causing the spindle 79 to threadits way into the housing 5 and engage the piston 23. This moves thepiston 23 forward and forces liquid out of the injector 1 into the airconditioning system. When the spring lock 13 re-engages the groove 83this can be felt by the operator and/or an audible click may be heard.The operator can check at the window 87 if the required dose has beeninjected. The cartridge 7 or 49 can be removed between uses or after ithas been emptied by reversing the process described above.

The injectors and components described herein may also be used to injectother liquids, for example, refrigerant, lubricant and/or otheradditives into an air conditioning system. The size of the componentsand the doses may need to be changed for practical use.

Referring to FIG. 22 a device or an injector 129 could have threads 131on the open end of a cartridge 133 in place of the flange 39. A housing135 would then have corresponding threads in place of the slots 63, 65,67, 69. The cartridge 133 could otherwise be similar to cartridge 7 orcartridge 49. The housing 135 could otherwise be similar to the housing5. Threads 131 would preferably be in the opposite direction of thethreads 59, 61 to limit unthreading the cartridge 129 from the housing135 when the injector 129 is in use.

Alternatively, the housing 135 could be formed as a single unit thatdoes not open. The housing 135 would have threads at opposite ends toreceive the driver 3 and the cartridge 129. An anti-reverse feature anda rotary position indicator feature could continue to be provided byaccessing latch 19 through the housing 135 to pull it out of the groove83 and permit the driver 3 to be reversed out of the housing 135 afteruse. It is a disadvantage of the unitary housing that the driver 3 mustbe manually threaded out of the housing. In split housing 5 it can besimply opened to allow removal or relocation of the driver 3.

Referring to FIG. 23, a device or an injector 137 (with driver 3 notshown) could have a bayonet-type mounting system 139, where housing 141has a fitted axial passageway 143 that permits the open end 8 of thecartridge 7 to pass into housing 141 when the cartridge 7 is in onerotary position, and not to pass into the housing when the cartridge 7is in another rotary position. In this system 139 the cartridge takesthe part of the bayonet and the housing 141 has bayonet receiversopening into the passageway 143 that permit the cartridge 7 to berotated into the second rotary while preventing axial motion of thecartridge 7. The housing 141 could be similar to the housing 5 with thepassageway 143 extending at least through to the bottom slots 63, 65.The flanges 39 with flats 43 (as they are asymmetrical about the axis ofthe cartridge) could perform the bayonet mount function on the cartridge7, while the slots 63, 65, 67, 69 could then be extended more fullyabout the axis to permit the flanges 39 to enter from the passageway143. Slot pair 67, 69 is shown in FIG. 23 with the hidden bayonetreceiver portion 145 shown in dash outline. The slots pairs 63, 65 and67,69 may not be fully annular (having a stops) so that the cartridge 7is not rotated back into line with the passageway 143. Once mounted,pressure from the driver 3 may tend to keep the cartridge 7 in place. Itmay be preferable to have supplementary means, such as a friction fit,spring lock mechanism or other means used in bayonet mounting systems.

An alternative bayonet mounting system 139 could be used, such asopposing pins that fit into a groove that initially opens parallel tothe longitudinal axis and then in an arc about the longitudinal axis.The pins could be on the housing 141 and the groove on the cartridge 7,or vice versa.

Again, the housing 141 could be a single unit that does not open asdiscussed for the housing 135. Having cartridges that are releasablymountable on a housing without having to open the housing, such as thosedescribed above, may be preferable in some applications or for someusers. Many other such releasable mounting systems are possible,including other bayonet mounting systems.

The injectors 129, 137 are used in a similar manner to the injector 1.It will likely be easier to mount the cartridges into the injectors 129,137 after the housing are closed. Obviously this will be necessary whenusing a unitary housing that does not open. It will also be necessary tothread the driver 3 into the housing when using a unitary housing. Thismay be done by choice if a split housing is used.

As mentioned previously, the injectors described herein may be used inmany applications in different configurations. Not all features arenecessary or beneficial in all applications. Having a positive indicatorof rotational position allows an operator to work quickly and accuratelywithout concern that too little or too much liquid will be injected. Alongitudinal indicator allows the operator to know how much liquid isbeing ejected (subtracting beginning and ending indications) and howmuch is left. The high accuracy features mean that the same amount offluid is ejected at all times and the back-pressure felt by the operatoris consistent, for repeatable accuracy. Reduction of waste materials andthe ability to recycle can also be significant benefits.

These benefits can be applied anywhere liquid is to metered. Forexample, two injectors could be used, one with epoxy resin and the otherepoxy hardener. These are typically applied in a given ratio, forexample 3:1. By having numerical indicators of dosage that are spacedapart three times on one injector as compared to the first, a user caneasily see eject the correct dosage of each liquid. A high accuracymetering device will improve the accuracy of the mix and the quality ofthe resulting product. In such an application it would typically not benecessary to have a connector, so the threads 30 could be removed andthe bevel 31. The profile of the tip 29 can be changed to suit theapplication. As well, the rounded shoulder 27 may not be required inlower pressure applications. In this case, the injectors are bettertermed manual liquid metering devices as the liquid will be ejected fromthe cartridge, but may not be injected into another system, pressurizedor otherwise.

It will be understood by those skilled in the art that this descriptionis made with reference to the preferred embodiment and that it ispossible to make other embodiments employing the principles of theinvention which fall within its spirit and scope as defined by thefollowing claims.

1. An injector for injecting a liquid into a pressurized system, theinjector comprising: a. a cartridge for containing the liquid, thecartridge having along its longitudinal axis an open end and an opposingpartially enclosed end with a connector for connection, directly orindirectly, to the pressurized system, b. a generally tubular housingfor receiving the open end of the cartridge, the housing having internalthreads, and c. a driver having external threads compatible with theinternal threads of the housing, and the driver having a handle, whereinthe housing includes internal threads and the housing is split into aplurality of releasably attached sections for access to the driver andcartridge, and an operator can manually grip the housing while rotatingthe driver with respect to the housing to force the liquid to be ejectedfrom the cartridge through the partially enclosed end.
 2. The injectorof claim 1 wherein the connector is a tip extending from the cartridge,the tip having external threads.
 3. The injector of claim 2 wherein thecartridge further comprises a piston having an external profile matchingthe internal profile of the cartridge in the tip, the piston enclosingthe open end of the cartridge to provide a chamber within the cartridgefor the liquid.
 4. The injector of claim 3 wherein the piston has a tipwithin the external profile, and the tip of the cartridge and the tip ofthe piston externally align when the piston is fully inserted into thecartridge.
 5. The injector of claim 1 wherein the handle and the housingwhere the housing is to be gripped are fully accessible to an operatorthroughout the travel of the driver into the housing.
 6. The injector ofclaim 1 wherein the housing has a slip resistant grip.
 7. The injectorof claim 1 wherein the releasably attached sections of the housingcomprise two longitudinal halves of the housing.
 8. The injector ofclaim 7 wherein the housing has a lock with a first and second position,the lock permitting opening of the housing halves when in the firstposition and the lock preventing opening of the housing halves when inthe second position.
 9. The injector of claim 8 wherein the lock and afirst of the housing halves have a slide and track mechanism to permitlimited motion of the lock between the first and second positions. 10.The injector of claim 8 wherein the second housing half has a tab which,when the housing is being hinged open or closed, can pass the lock whenthe lock is in the first position and cannot pass the lock when the lockis in the second position.
 11. The injector of claim 8 wherein the lockhas a lock spring that tends to keep the lock closed when the lock isclosed and tends to keep the lock open when the lock is open.
 12. Theinjector of claim 1 wherein the cartridge and housing have anti-rotationmeans to prevent rotation of the cartridge with respect to the housingabout the longitudinal axis of the housing.
 13. The injector of claim 1wherein the housing and driver have rotary position indicator means thatprovide an indication of the rotary position of the driver with respectto the housing.
 14. The injector of claim 13 wherein the rotary positionindicator means provides an audible click when aligning to a selectedrotary position.
 15. The injector of claim 1 wherein the housing anddriver have anti-reverse means that prevent the rotary movement of thedriver with respect to the housing about the longitudinal axis of thehousing in one direction, while permitting such motion in the otherrotary direction.
 16. The injector of claim 1 wherein the driver has alongitudinal groove in the threads and the housing has a lock springwith a latch that springs into the groove when the groove and latch arealigned and that is pushed away by the threads when the groove and latchare not aligned.
 17. The injector of claim 16 wherein the groove has asubstantially perpendicular leading edge, and the latch has a sharplyinclined trailing edge.
 18. The injector of claim 17 wherein the springlock is sufficiently stiff to provide an audible click when the latchenters the groove.
 19. The injector of claim 1 wherein the cartridge andhousing have differentiation means to permit the housing todifferentiate between cartridges of different capacities.
 20. Theinjector of claim 1 wherein the housing has a plurality of locations forcartridges of different capacities.
 21. The injector of claim 20 whereinthe housing locations are different to permit the housing todifferentiate between cartridges of different capacities.
 22. Theinjector of claim 1 wherein the housing and driver have longitudinalindicator means that indicate the amount of liquid remaining in thecartridge.
 23. The injector of claim 1 wherein the driver has indicatorslongitudinally spaced along its surface.
 24. The injector of claim 1wherein the driver has numerical indications longitudinally spaced alongits surface.
 25. The injector of claim 1 wherein the releasably attachedsections are split longitudinally.
 26. The injector of claim 25 whereinthe sections are longitudinally hinged.
 27. The injector of claim 26wherein the housing has a lock with a first and second position, thelock permitting hinged opening of the sections when in the firstposition and the lock preventing opening of the sections when in thesecond position.